/*======================================================================*
    Copyright (c) 2015-2022 DTS, Inc. and its affiliates.

    Redistribution and use in source and binary forms, with or without modification,
    are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
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    2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
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    may be used to endorse or promote products derived from this software without
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    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 *======================================================================*/

#ifndef OBSERVABLESTATE_H
#define OBSERVABLESTATE_H

#include <string>
#include <vector>

#include "boost/thread/thread.hpp"

#include "DataTypes.h"

namespace SMPTE_SYNC
{
    
    /**
     * @brief StateObserver class provides a base class for observering state changes.
     *
     */

    class StateObserver
    {
    public:
        
        /// Constructor
        StateObserver()
        {
        }
        
        /// Destructor
        virtual ~StateObserver()
        {
        }

        /// Override to receive notifications for state changes.
        virtual void NotifyStateChange(void) = 0;
    };

    /**
     * @brief StateObserver class provides a base class for observering state changes. Threadsafe.
     *
     */

    class ObservableState
    {
    public:

        /// Constructor
        ObservableState();

        /// Destructor
        virtual ~ObservableState();
        
        /// Adds a StateObserver
        void AddObserver(StateObserver *iCallback);

        /// Removes a StateObserver
        void RemoveObserver(StateObserver *iCallback);

    protected:
        
        /// Called by inherited classes to trigger notifications of state changes for all observers.
        void NotifyStateChange(void);
        
    private:

        /// Mutex to protect multi-threaded access to observers_
        boost::mutex        observersListMutex_;

        /// Vector of StateObserver pointers
        std::vector<StateObserver*> observers_;
    };

}  // namespace SMPTE_SYNC

#endif // OBSERVABLESTATE_H
